690.12(B)(2) Rapid Shutdown. Inside the Array Boundary.
Code Change Summary: Revised code language provides clarity on PV system rapid shutdown and hazard control inside the array boundary.
In the 2020 NEC®, “Rapid Shutdown” inside the array boundary has been revised to address “PV hazard control systems”.
Section 690.12(B)(2) provides requirements to ensure that first responders are safe once the PV hazard control system has been initiated.
Firefighters (first responders) often arrive to a building fire and immediately kill all power to the building so they can enter the building or cut vents in the roof system as they try to put out the fire. A roof-mounted PV system can create a hazard for a fire fighter cutting vents in the roof system. Firefighters have no desire to cut through the roof into live DC PV circuits that may be energized after the power has been disconnected to a building.
PV hazard control and rapid shutdown is critical to ensure that live DC conductors are reduced to a low enough voltage level that a firefighter cutting into a roof and coming in contact with an energized DC circuit is not exposed to a shock hazard.
In the 2020 NEC®, there are three options to comply with the rapid shutdown control limits required in 690.12(B)(2) inside the array boundary:
- Install a PV hazard control system listed for the purpose.
- Limit the controlled conductors inside the array boundary to not more than 80 volts within 30 seconds of rapid shutdown initiation.
- Install the PV arrays so that they have no exposed wiring methods or conductive parts and install them more than 8 feet from exposed grounded conductive parts or ground.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.
2017 Code Language:
690.12(B)(2) Inside the Array Boundary. The PV system shall comply with one of the following:
(1) The PV array shall be listed or field labeled as a rapid shutdown PV array. Such a PV array shall be installed and used in accordance with the instructions included with the rapid shutdown PV array listing or field labeling.
Informational Note: A listed or field labeled rapid shutdown PV array is evaluated as an assembly or system as defined in the installation instructions to reduce but not eliminate risk of electric shock hazard within a damaged PV array during fire-fighting procedures. These rapid shutdown PV arrays are designed to reduce shock hazards by methods such as limiting access to energized components, reducing the voltage difference between energized components, limiting the electric current that might flow in an electrical circuit involving personnel with increased resistance of the conductive circuit, or by a combination of such methods.
(2) Controlled conductors located inside the boundary or not more than 1 m (3 ft) from the point of penetration of the surface of the building shall be limited to not more than 80 volts within 30 seconds of rapid shutdown initiation. Voltage shall be measured between any two conductors and between any conductor and ground.
(3) PV arrays with no exposed wiring methods, no exposed conductive parts, and installed more than 2.5 m (8 ft) from exposed grounded conductive parts or ground shall not be required to comply with 690.12(B)(2).
The requirement of 690.12(B)(2) shall become effective January 1, 2019.
2020 Code Language:
690.12(B)(2) Inside the Array Boundary. The PV system shall comply with one of the following:
(1) A PV hazard control system listed for the purpose shall be installed in accordance with the instructions included with the listing or field labeling. Where a hazard control system requires initiation to transition to a controlled state, the rapid shutdown initiation device required in 690.12(C) shall perform this initiation.
Informational Note: A listed or field-labeled hazard PV control system is comprised of either an individual piece of equipment that fulfills the necessary functions or multiple pieces of equipment coordinated to perform the functions as described in the installation instructions to reduce the risk of electric shock hazard within a damaged PV array for fire fighters. See UL 3741, Photovoltaic Hazard Control.
(2) Controlled conductors located inside the boundary shall be limited to not more than 80 volts within 30 seconds of rapid shutdown initiation. Voltage shall be measured between any two conductors and between any conductor and ground.
(3) PV arrays shall have no exposed wiring methods or conductive parts and be installed more than 2.5 m (8 ft) from exposed grounded conductive parts or ground.